Voyager 2, the venerable space probe launched in 1977, “stopped” last week.
Don't dig up your cache of food or prepare to welcome our Oort Cloud Overlords: the pause is a result of celestial mechanics.
As the Tweet below explains, Voyager 2 is heading on its merry way and Earth is swinging around Sol as usual. But last week the two bodies matched velocities so Voyager didn't get any further away from us.
There's nothing unusual about this. Indeed, there are times when the two Voyagers get a little closer to us. But this is definitely a one step back, two hundred steps forward kind of affair as both Voyagers are belting along at several kilometres a second with one-way tickets to wherever gravity and momentum will take them.
The Earth is traveling towards me as fast as I am receding right now. That is why I would seem to have come to a stop! Soon that will change— NSFVoyager2 (@NSFVoyager2) June 3, 2015
Both craft have years of fuel left and are still in touch with Earth, albeit over anaemic data links. But that's not stopping mission boffins from working with the craft: Voyager 2 last week tested several of its instruments, a process that requires it to enter a “Command Moratorium Temperature Stabilization Period” during which it heats its radio to make sure it is ready to receive commands from Earth.
Over the last week the craft has tested its Gyro and recalibrated several of its instruments. It's also travelled another light second, placing it 14 hours, 54 minutes and five seconds from home.
I am currently 14 hrs 54 min 05 secs of light-travel time from Earth (2015:159:000000:2L)— NSFVoyager2 (@NSFVoyager2) June 8, 2015
Voyager 2 visited Jupiter, Saturn, Neptune and Uranus. The craft is expected to keep sending back data until 2025, when its plutonium-powered radioisotope thermoelectric generators will no longer produce enough power for it to operate any instruments.
Even then, the craft's mission will continue thanks to the “golden record” it bears. The record contains information about Earth and its human, plant and animal inhabitants, plus music and a message from former US President Jimmy Carter, among other material. The record comes complete with a stylus and is designed to be interpretable by another technological civilisation. ®